My long-term objective is to understand the mechanism of receptor-mediated glucocorticoid action. Glucocorticoids are important both as immunosuppressive and anti-inflammatory agents and as therapeutic tools in the treatment of leukemias and lymphomas. Currently, knowledge is far from complete regarding the etiology and/or control of steroid-sensitive tumor cells, the molecular mechanism of steroid-induced responses in neoplastic on normal cells, or the route by which some cells escape hormonal control. This is due in part to the nature of traditional methods of steriod receptor study in that they have relied on indirect detection strategies requiring the formation and maintenance of steroid-receptor complexes, and are usually performed in cell- free systems. The purpose of this project is to develop and evaluate a novel experimental system in which the molecular and cellular biology of steriod hormone action will be directly probed in living cells. The biological probes to be introduced into the system are 1) monoclonal antibodies that bind to an array of epitopes on, and modify function of the glucocorticoid receptor, and 2) the immunoaffinity-purified intact receptor and its discrete fragments containing specific functional domains. A refined strategy based on the erythrocyte ghost-mediated method will then be used to "inject" large numbers of these biologically active macromolecules into bulk cultures of glucocorticoid- responsive and resistant tumor cells. As formulated, this experimental system possesses marked versatility, and thus will make feasible novel in vivo receptor neutralization, competition, and replacement studies in any of the available glucocorticoid- responsive and variant resistant cell lines. The antibody bank I hope to develop should also provide the basis of powerful new analytical procedures and allow new insight into the structure and function of the glucocorticoid receptor in particular, and steroid receptors in general.